Wondering if anyone knows any decent websites that sell PC Case's with Water Cooling aready in?. I have heard about the Gigabyte Mercury 3D Case which has Water Cooling Bulit in, but heard its not that good.

Honestly it's not worth it. Often stock kits in cases will have one type of metal in the radiator and the blocks you'll buy for cpu/gpu another causing corrosion. It's really not hard to build a kit, we can even show you what parts you need if you give us a price limit.